Edge grinder for mechanically rounding off edges of structural members

ABSTRACT

An edge grinding device for rounding off edges of members which are passed through the grinding device. The device includes a main frame for supporting the structural member, and a grinding aggregate which is pivotably mounted on the frame about an axis running substantially parallel to the directional motion of the member, the grinding aggregate having a grinding element which has a convex grinding surface, wherein the grinding aggregate pivots the convex grinding surface about the edge which is to be round while the member is moving through the device.

The present invention relates to an edge grinding device formechanically rounding edges of structural members which are passedthrough said edge grinding device, comprising a main frame having, inrelation to the direction of travel, transversally extending supportrollers upon which the structural member is supported and is drivenforward.

An edge grinder of this type is known from NL-9002175.

The purpose of the invention has been to provide a machine for roundingoff edges of structural members, such as rolled steel sections andsheets. Today it is a requirement in offshore structures that all edgesof steel sections have a radius of curvature of at least 2 mm andsometimes more. This is due to maintenance and corrosion protection. Sofar, this rounding-off procedure has usually been carried out manuallyby means of an angular grinder or facing machine.

It is documented by tests that the principle on which the present edgegrinding device is based provides a very good quality in the roundingoff of steel section edges and far exceeds the quality achieved today byangular grinders.

In accordance with the present invention there has been provided an edgegrinding device of the introductory part of this description,characterized by having at least one grinding aggregate with a movablegrinding element, said grinding aggregate being pivotally mounted on aframe about an axis which runs substantially parallel to the advancementaxis of the structural member, said pivotal axis being located outsidethe structural member, that the cross-sectional profile of the grindingelement has a predetermined geometric form adapted to the location ofthe pivotal axis and the radius of curvature of the rounding of theedges, and that the grinding element is pressed yieldingly orresiliently against the edge.

Such a design entails, inter alia, that the grinding element will beworn down evenly throughout its entire crosswise area, thus providing along useful lifetime to the individual grinding element beforereplacement.

It is contemplated that the grinding aggregate can be in the form of amotor operated grinding wheel having a predetermined geometricallyconfigured surface, but it has proved to be advantageous that thegrinding aggregate is in the form of a belt grinder or belt sander inwhich a grinding belt or sand belt runs between and around two rollers.

Even though it is actually unnecessary to have more than one grindingaggregate for each edge grinding device, such an aggregate mayadvantageously be mounted on each side of the structural member forsimultaneous grinding of two edges.

Advantageously, two more grinding aggregates may be mounted on each sideof the structural member downstream of the first grinding aggregate orthe first pair of grinding aggregates, for simultaneous grinding of twoadditional edges in one run, such as grinding edges of steel beamshaving an I or H section.

The edge grinding device may advantageously comprise vertically andhorizontally mounted guiding rollers for controlled guidance of thestructural member through the edge grinding device. Advantageously, thegrinding aggregate may comprise air nozzle means for air supply and forthe formation of an air cushion between the grinding shoe of thegrinding aggregate and the grinding belt, so as to reduce the frictionand/or cool the grinding belt.

It is expedient that each grinding aggregate has an independent power ormotor operation. Further, each grinding shoe can be pressed against theedge or be raised or lowered by an apparatus, such as a fluid poweredcylinder, for the purpose of regulating the grinding pressure, and thusprovide a yielding or a certain resiliency in relation to the edges ofthe structural member so as to absorb any roughness therein,simultaneously with the grinding element being fed toward the edge asthe metal is ground away.

Each grinding aggregate is advantageously pivotable by means of a linkmechanism and a fluid power cylinder about said pivotal axis, thusmaking a kind of pendulum movement.

Other and additional objects, features and advantages will be apparentfrom the following description of one, at present preferred embodimentof the invention, which is presented for the purpose of description,without thereby limiting the invention, in connection with the encloseddrawings wherein:

FIG. 1 shows in perspective view an embodiment of the edge grindingdevice according to the present invention having four independentgrinding aggregates;

FIG. 2A shows schematically a side view of the edge grinding deviceaccording to FIG. 1 having a forward grinding section 1 and a reargrinding section 2;

FIG. 2B shows schematically an end view of the edge grinding deviceaccording to FIG. 2A having the grinding section 1 on the left side andthe grinding section 2 on the right side;

FIG. 3A shows schematically the pendulum movement in the grindingsection 1;

FIG. 3B shows schematically the pendulum movement in grinding section 2;

FIG. 4 shows a schematic side view of the grinding shoe in the grindingaggregate;

FIG. 5 shows an end view of the grinding shoe according to FIG. 4;

FIGS. 6A-6D show schematically the geometric design of the grinding areaand the pendulum movement that it performes; and

FIG. 7 shows the material that is ground away, and the center of rdiscloses the point where it would normally be considered natural toplace the pivotal axis of the grinding aggregate.

FIG. 1 is a depiction in perspective of the edge grinding device 20according to the invention. The edge grinding device 20 is structured ona main frame 1, resting on the ground. On said main frame 1 there aremounted three support rollers 7 which shall support a structural member19 which is advanced through the edge grinding device 20. For lateralcontrol of the structural member 19 through the edge grinder 20 guidingrollers 8 are mounted on each side of the travelling path of thestructural member 19. In addition, guiding rollers 9 are provided havinghorizontal rotational axes. The guiding rollers 8 and 9 allow forcontrolled movement of the structural member 19 through the edge grinder20. Four grinding aggregates 10 are pivotally attached to the mainframe 1. Each grinding aggregate 10 is operated by its respective motor17 which preferably is operated in complete independence of the others,and is able run in both directions.

FIG. 2A shows a side view of the edge grinder 20. The edge grinder 20,in this embodiment, has a front grinding section 1 and a back grindingsection 2. Each grinding section has two grinding aggregates 10, one oneach side of the structural member 19. With a total of four grindingaggregates 10 four edges may be rounded off simultaneously. Eachgrinding aggregate 10 comprises two driving wheels 11 around which agrinding belt 13 runs. The sand belt or grinding belt 13 also runsacross a grinding shoe 12. Said grinding shoe 12 may be raised orlowered to alter the bias of the grinding belt 13 against the edge ofthe structural member 19 by means of a grinding pressure cylinder 14.The grinding shoe 12 is rotatably mounted by means of extensions 21. Onedriving wheel 11 may be monitored by a fluid powered cylinder 15 fortensioning the grinding belt 13. The arrow D shows the normal feedingdirection of the structural member 19. The arrows R1 and R2 show,respectively, the direction of the grinding belt 13 in grinding sections1 and 2 during operation of the aggregate 10. As previously mentioned,it is understood that the belt 13 can be run in both directions.Moreover, additional edges of the structural member 19 can be ground onreturn through the machine (in the opposite direction of the arrow D).

It is to be understood that in one embodiment the edge grinder mayconsist of only one grinding section 1, alternatively of only the othergrinding section 2. As yet another alternative the edge grinder mayconsist of only one grinding aggregate, optionally three. If all eightedges of an I-beam are to be ground in one run, eight grindingaggregates would be needed, preferably mounted in four grindingsections.

Each grinding aggregate 10 is secured to a carrier section 2 which isagain secured to the main frame 1.

FIG. 2B shows an end view of the edge grinder 20 having the grindingsection 1 on the left side and the grinding section 2 on the right sideof a dotted centre line 23. At grinding section 1 the lower edge of thelower flange of the structural member 19 is ground. In section 2 theupper edge of the lower flange of the structural member. 19 is roundedoff. The grinding aggregate 10 can be pivoted about a pivotal axis 22running parallel to the feeding direction of the structural member 19and thus in the longitudinal direction. The pivotal movement, or thependulum movement, of the grinding aggregatee 10 is effected by apendulum cylinder 16 illustrated by a dotted line. Furthermore, thegrinding aggregates 10 can be moved away from each other or toward eachother by means of a transverse cylinder 4 which is attached to itsrespective part of the carrier section 2. The carrier section 2 moves onthe transverse guides 3.

The pendulum movement of the grinding aggregates 10 is further shown inFIG. 3A for grinding section 1, and FIG. 3B for grinding section 2. Notethat the pivotal axis 22 of the grinding aggregate 10 lies outside thestructural member 19, and by means of this position and the geometricdesign of the bearing surface of the shoe 12, shown in FIG. 6, it ispossible to form finely rounded edges on the structural member 19.

FIG. 4 shows in further detail the grinding shoe 12. This comprises oneor more air nozzle means 24 for supply of pressurized air via the supplytube 25. By means of this air an air cushion is formed between thegrinding shoe 12 and the grinding belt 13. Simultaneously, the air willcool the grinding belt 13.

FIG. 5 shows an end view of the grinding shoe 12 according to FIG. 4.The whole unit is secured to the carrier section 2. The grindingpressure cylinder 14 can increase/decrease the bias of the grinding belt13 against the structural member 19.

FIGS. 6A-6D show schematically a cross-sectional view of the verysurface of the grinding shoe 12 along which the grinding belt 13 runs.The drawings show how the grinding shoe 12 makes a pendulum movementfrom one exterior side to the other, for example making an arc of 60° intotal. Simultaneously, the pendulum suspension means, i.e., theextensions 21 and cylinder 14 in FIGS. 4 and 5, ensures a resilience ofthe grinding shoe 12. The resilient movement is suggested by an A inFIGS. 6B, 6C and 6D. The cylinder 15 ensures correct tensioning of thegrinding belt 13. The pressure of the cylinders 14 and 15 must becoordinated. When the cylinder 14 urges the shoe 12 upward, the cylinder15 must give way correspondingly in order to retain the tension of thebelt.

It is to be understood that the embodiment of the grinding shoe 12,i.e., its cross-sectional profile, is of crucial importance in obtaininga good grinding result. Tests have shown that it is important that thegrinding shoe 12 urges the grinding belt 13 heavily against the edge tobe ground and that the belt 13 be fed to the edge as the material isground away. This is achieved by the fact that the grinding shoe 12 isresilient and also capable of following possibly uneven/curved surfacesof the structural member 19. Moreover, as noted, cooling shouldpreferably be provided, otherwise the grinding belt 13 will become sohot that it breaks at the Joint. FIGS. 6A-6D may also, in principle,represent the surface configuration of a rotatable grinding wheel as analternative to a belt grinder.

In order to obtain a satisfactory grinding result a further aspect isimportant, viz., the geometry of the movement of the grinding shoe 12.This comes in addition to the design of the form of the grinding shoe,which must be somewhat curved. When a rounding-off radius of, forexample, 2 mm is to be achieved, it would seem appropriate that therotational center of the grinding shoe 12 be positioned at the center ofr₁ as shown in FIG. 7. However, in terms of structure the disadvantageis that the point of rotation then must be positioned inside thematerial to be ground. Tests that have been made show that this ispossible in simply practical terms, but in terms of operation andmaintenance it will be a cumbersome method. In addition, wear and tearof the grinding element will be concentrated, which must be exchangedmore frequently. For a belt grinder this disadvantage could be remediedby tilting the grinding aggregate and thereby the grinding belt somewhatin relation to the edge of the structural member 19. FIGS. 6A-6D thusshow how this problem has been solved. The grinding shoe 12 moves aroundthe rotational center 22, and with respect to the shape of the grindingshoe, there are two parameters, viz., the curves radius r₂ and the angleα. The angle α and the curves radius r₂ form a relationship ofdependency upon the distance a between the edge of the structural member19 and the rotational center 22. It is suggested that the angle α shouldbe in the range of 10° and 20°, and in a prototype an angle α=14° hasbeen found advantageous. The corresponding radius of survature is thenr₂ =27 mm, and the deflection of the angle in the pendulum movement is30° on each side, i.e., 60° in total. In addition the "resilience" A isan important parameter which provides additional feeding as the materialof the edge (see FIG. 7) is ground away.

I claim:
 1. An edge grinding device for mechanically rounding off anedge of a structural member (19) which is passed through said edgegrinding device (20), the device comprising:a main frame (1) having, inrelation to the direction of travel D, transversally extending supportrollers (7) upon which the structural member (19) is supported and isdriven forward, at least one grinding aggregate (10) having a movablegrinding element (13), said grinding aggregate (10) being pivotallymounted on a pivot on said frame, said pivot having an axis runningsubstantially parallel to the direction D and located outside thestructural member (19), a fluid powered cylinder for pivoting saidgrinding aggregate, wherein a cross-sectional profile of the grindingelement (13) is convex relative to the edge, and wherein the grindingelement is pressed resiliently against the edge when the structuralmember (19) is passed through the device.
 2. An edge grinding deviceaccording to claim 1, wherein the grinding aggregate (10) comprises abelt grinder, and the grinding element is a belt having itscross-sectional profile defined by a convex grinding shoe (12) acrosswhich the grinding belt runs.
 3. An edge grinding device according toclaim 1, wherein the grinding aggregate comprises a rotating grindingwheel having said convex cross-sectional profile.
 4. An edge grindingdevice according to claim 1, comprising at least two of said grindingaggregate (10) for simultaneous grinding of two of the edges.
 5. An edgegrinding device according to claim 4, comprising at least four of saidgrinding aggregate for simultaneous grinding of four of the edges.
 6. Anedge grinding device according to claim 2, wherein said grindingaggregate (10) comprises air nozzle means (24) for forming an aircushion between the grinding shoe (12) and the grinding belt (13).
 7. Anedge grinding device according to claim 4, wherein each said grindingaggregate (10) has its own operating motor.
 8. An edge grinding deviceaccording to claim 2, further comprising a further fluid poweredcylinder (14) connected to said grinding shoe for regulating thegrinding pressure.
 9. A grinding device for grinding an edge of amember, the device comprising:a frame for slidably supporting the memberto be ground as the member is moved through the device; a grindingaggregate with a grinding element for grinding an edge of the member,said grinding element having a grinding surface which is convex relativeto the edge of the member; a pivot attached to said frame and saidgrinding aggregate for pivoting said grinding surface through an arc sothat the edge of the member is rounded by the pivoting grinding surfacewhen the member is moved through the device.
 10. The device of claim 9,wherein said grinding element is a belt and said grinding aggregatefurther comprises a shoe with a convex surface across which saidgrinding element runs, thereby forming the convex shape of said grindingsurface.
 11. The device of claim 10, wherein said grinding aggregatefurther comprises a grinding pressure cylinder attached to said shoe forpushing said grinding surface against the edge to be ground.
 12. Thedevice of claim 9, wherein an axis of said pivot is a first distancefrom the edge to be ground, and wherein the convex shape of saidgrinding surface includes a center rounded portion with a radius smallerthan said first distance and two tangential edge portions extending fromopposing sides of said center portion.
 13. The device of claim 12,wherein an angle between one of said tangential edge portions and anextension of the other of said tangential edge portions is from 10° to20°.
 14. The device of claim 9, wherein an axis of said pivot is asubstantially parallel to a direction of movement of the member.